Under-Secretary-General for Political Affairs Jeffrey Feltman told the Sri Lankan government the people behind the violence should be brought to justice.
During his visit Feltman "condemned the breakdown in law and order and the attacks against Muslims and their property", a UN statement said.
Feltman, who met with local Muslim leaders to show solidarity, "urged swift and full implementation of the government's commitment to bring the perpetrators of the violence and hate speech to justice, to take measures to prevent recurrence, and to enforce non-discriminatory rule of law".
Violent attacks against Muslims swept the central district of Kandy over the last week.
The violence, triggered by the death of a Sinhalese Buddhist man after being beaten by a group of Muslim men over a traffic dispute, left at least two dead with and mosques, dozens of homes, and businesses torched or destroyed.
Several dozen people were wounded in the riots.
Authorities declared a state of emergency and imposed a curfew in an attempt to curtail the violence, but Sri Lankan Muslims told Al Jazeera they were concerned the attacks would continue.
Police have arrested the suspected instigators of the riots.
On Saturday, President Maithripala Sirisena announced a three-member panel will be appointed to investigate and lifted the curfew. However, soldiers remained in the streets.
The violence has raised fears of instability in Sri Lanka, a South Asian island nation still struggling to recover from nearly three decades of ethnic civil war.